/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.hydraql.benchmark.core;

import java.io.IOException;
import java.io.InputStream;

/**
 * A ByteIterator that iterates through an inputstream of bytes.
 */
public class InputStreamByteIterator extends ByteIterator {
  private final long len;
  private final InputStream ins;
  private long off;
  private final boolean resetable;

  public InputStreamByteIterator(InputStream ins, long len) {
    this.len = len;
    this.ins = ins;
    off = 0;
    resetable = ins.markSupported();
    if (resetable) {
      ins.mark((int) len);
    }
  }

  @Override
  public boolean hasNext() {
    return off < len;
  }

  @Override
  public byte nextByte() {
    int ret;
    try {
      ret = ins.read();
    } catch (Exception e) {
      throw new IllegalStateException(e);
    }
    if (ret == -1) {
      throw new IllegalStateException("Past EOF!");
    }
    off++;
    return (byte) ret;
  }

  @Override
  public long bytesLeft() {
    return len - off;
  }

  @Override
  public byte[] toArray() {
    int size = (int) bytesLeft();
    byte[] bytes = new byte[size];
    try {
      if (ins.read(bytes) < size) {
        throw new IllegalStateException("Past EOF!");
      }
    } catch (IOException e) {
      throw new IllegalStateException(e);
    }
    off = len;
    return bytes;
  }

  @Override
  public void reset() {
    if (resetable) {
      try {
        ins.reset();
        ins.mark((int) len);
        off = 0;
      } catch (IOException e) {
        throw new IllegalStateException("Failed to reset the input stream", e);
      }
    } else {
      throw new UnsupportedOperationException();
    }
  }

}
